1. Field of the Invention
This invention relates to electronic organs and in particular to means for producing percussive musical tones in electronic organs.
2. Description of the Background Art
In U.S. Pat. No. 3,022,695, Richard E. Williams shows a percussion circuit having means for differentiating rectangular keying pulses to produce pulses for controlling the gain of an amplifier to which a rectangular waveform tone signal is provided. The system utilizes key-controlled electric light sources with photoelectric means for intercepting light from the light sources with a modulating device modulating the light from each of the light sources according to a musical tone.
Richard H. Peterson shows an electronic musical instrument in U.S. Pat. No. 3,178,499, having diode gate means for applying an envelope to a tone signal in an electronic organ. The diode is used as a portion of a voltage divider and the circuit includes a capacitor for distorting the tone signal waveform. The circuit removes higher order harmonics from the tone signal without effecting any clipping thereof.
Michael R. Harris shows a touch percussion means for an electronic organ with back-to-back diode gates in U.S. Pat. No. 3,558,796. In this circuit, the diode gate operates as a linear modulator and applies an envelope to the tone-colored signal. The system utilizes percussive gates as tone generators wherein the tone signals are passed through a slow percussive linear diode gate to the amplifier and loudspeaker.
In U.S. Pat. No. 3,655,904 of Herbert Cohen, an electric variable tone percussion instrument is disclosed wherein a diode bridge modulator is provided which is controlled by an exponentially decaying voltage applying a percussive envelope to the square wave signal. Switching means are provided for discharging a storage means to provide the exponentially decaying signal across the output means.
John R. Brand et al show an electrical musical instrument in U.S. Pat. No. 3,422,454 wherein a circuit using a diode to clip the rectangular output of a tone generator is utilized to vary the level of the output as a function of time, thereby to apply a percussive envelope to the signal. The envelope is produced by differentiating a keying pulse to produce a sawtooth signal, which is subsequently filtered and applied to the clipping diode. The tone generator signal is not differentiated prior to the clipping. The output signal is passed through a voicing filter after clipping.
Ralph L. Dodds et al, in U.S. Pat. No. 3,593,187, show a noise generator and actuating circuit for a musical instrument for reproducing percussion sounds and the like. A noise generator and noise voicing network is provided for electronically generating white noise which is formed with regard to frequency response and waveform envelope shape to provide a plurality of different voice signal outputs. The noise output signals are varied and controlled by controlling the supply voltage to the noise generator.
Kiyoshi Ichikawa shows a rim-shot-sound-producing device for an electronic organ in U.S. Pat. No. 3,636,801. A percussive sound wave is provided to a clipper circuit and then passed through a differentiation circuit to provide a percussive signal having a richer harmonic content in the beginning portion than in the final portion.
In U.S. Pat. No. 3,637,913 of Chauncey R. Evans, a tone generator is disclosed which provides an asymmetrical rectangular wave having a duty cycle of at least four to one. The rectangular wave is fed to a clipping diode gate where it is modulated in accordance with a signal envelope generated by the player of the piano. A capacitor is connected across the modulator output or within the modulator to provide a modulated rectangular wave with a substantially sawtooth waveform.